HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT       #4803

PERIOD COVERED: 5am March 3 - 5am March 4, 2009 (DOY

                           062/1000z-063/1000z)

OBSERVATIONS SCHEDULED

ACS/SBC 11980

Deep FUV Imaging of Cooling Flow Clusters

We propose to take deep ACS FUV images of a carefully selected sample of

19 bright central galaxies in nearby galaxy clusters. This program is

the last critical element of a comprehensive investigation of the impact

of stellar and AGN feedback on the local galaxy cluster environment. The

HST images will complement new, high-resolution, Halpha images obtained

with the recently commissioned Maryland-Magellan Tunable Filter (MMTF)

on the Baade 6.5m telescope, archival Chandra, VLA, and GALEX data, and

on-going H2/NIR observations. The MMTF data have revealed unsuspected

filamentary complexes in several systems. The GALEX data often show

hints of extended NUV and FUV emission on a similar scale, but their

poor spatial resolution prevents meaningful comparison with the MMTF

data. The HST data will provide this much needed gain in resolution. The

combined radio-H2-Halpha-FUV-X-ray dataset will allow us to derive with

unprecedented precision the role of the AGN, hot stars, shocks, and

relativistic particles on the excitation and thermodynamics of the

multi-phase intracluster and interstellar media in these systems. This

is an important question since the formation and evolution of most

cluster galaxies have likely been affected by these processes.

WFPC2 11972

Investigating the Early Solar System with Distant Comet Nuclei

We propose 85 orbits of imaging observations with the WFPC2 to get

nucleus size estimates for 8 well observed dynamically new and

long-period comets at large distances from the sun when their activity

levels are low. This will increase the sample of these nucleus sizes by

nearly 50%, but will more than double the selection of comets for which

we can run thermal models. Small icy bodies are the best preserved

remnants of planet formation, and we have recently found that

observationally constrained thermal models can distinguish differences

in microphysical properties of comet nuclei. The new HST data will

enable the first exploration of physical conditions in different regions

of the early solar nebula.

WFPC2 11981

FUV Imaging Survey of Galactic Open Clusters

We propose a WFPC2 FUV imaging survey of 6 Galactic open clusters with

ages ranging from 1 Myr to 300 Myr complemented with NUV/optical imaging

of the same fields. No such survey has ever been attempted before in the

FUV at the resolution of WFPC2 (indeed, no WFPC2 FUV images of any

Galactic open cluster exist in the HST archive) and, since WFPC2 will be

retired in SM4 and none of the other HST instruments can do FUV imaging

of bright objects, this is the last chance to do such a survey before

another UV telescope is launched. This survey will provide a new

perspective on young/intermediate age Galactic clusters and a key

template for the study of star formation at high redshift, where the

intensity peak we observe in the optical/NIR from Earth is located in

the FUV in its rest frame. For clusters still associated with an H II

region, UV imaging maps the continuum emission of the ionized gas and

the radiation scattered by background dust and, combined with optical

nebular images, can be used to determine the 3-D structure of the H II

region. For all young clusters, FUV+NUV+optical photometry can be used

to study the UV excesses of T-Tauri stars. For clusters older than ~40

Myr, the same photometric combination is the easiest method to detect

companion white dwarfs which are invisible using only the optical and

NIR. WFPC2 is also an excellent instrument to discover close companions

around bright stars and improve our knowledge of their multiplicity

fraction. Finally, for all clusters, the combination of

high-spatial-resolution UV and optical photometry can be used to

simultaneously measure the temperature, extinction, extinction law,

distance, and existence of companions (resolved and unresolved) and,

thus, produce clean HR diagrams with resolved cluster membership and

much-reduced systematic uncertainties.

WFPC2 11983

An Imaging Survey of Protoplanetary Disks and Brown Dwarfs in the

Chamaeleon I region

We propose to carry out a HST/WFPC2 survey of young brown dwarfs, Class

I and Class II sources in the Chamaelon I region, one of the

best-studied star-forming regions, in order to investigate the link

between disk evolution and the formation of substellar-mass objects. We

will use deep broad-band imaging in the I and z-equivalent HST bands to

unveil the unknown population of substellar binary companions, down to a

few Jupiter masses for separations of a few tens of AU. We will also

perform narrow-band imaging to directly detect accreting circumstellar

disks and jets around brown dwarfs, Class-I and class-II objects.

Chamaelon I is nearly coeaval of Orion (~1-2Myr) but at ~1/3 its

distance, allowing 3x higher resolution and 10x more flux for comparable

objects. Unlike Orion, low-mass objects and protoplanetary disks in

Chamaeleon I have been extensively studied with Spitzer, but not yet

with the HST. The Chamaeleon I region is an ideal HST target, as it lies

in the CVZ of the HST and therefore it is easily accessible any time of

the year with long orbits.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports

of potential non-nominal performance that will be investigated.)

HSTARS: (None)

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                       SCHEDULED      SUCCESSFUL

FGS GSAcq               05                   05                          

FGS REAcq               09                   09        

OBAD with Maneuver 30                   30

SIGNIFICANT EVENTS: (None)